1. Field of the Disclosure
The present disclosure relates to estimating one or more parameters of interest relating to an earth formation. In one aspect, the present disclosure relates to a method of determining one or more parameters relating to the earth formation ahead of a selected location in a borehole.
2. Background of the Art
Exploration and production of hydrocarbons generally requires drilling a borehole into the earth. The borehole can be used to gain access to depths of the earth for performing measurements related to the exploration and production.
Well logging is a technique used to perform the measurements in the borehole. In well logging, a logging tool is conveyed through the borehole. For “logging-while-drilling” (LWD), a logging tool is coupled to a drill string. Thus, the measurements can be performed while the borehole is being drilled, during interruptions in drilling, or as the drill string is conveyed along the borehole. In post drilling applications, a logging tool may be conveyed via a non-rigid carrier such as a wireline in order to log the earthen formation. Generally speaking, logging tools may transmit signals into the earthen formation and then detect reflected signals and/or the response of the earthen formation to the transmitted signals.
In some situations, it may be desirable to have a tool that is predominantly sensitive to the one or more formation features downhole of the selected downhole location and, at the same time, is minimally affected by the formation properties uphole the selected downhole location.